Hi, I have developed a TMDb client application for android - https://filmseeker.firebaseapp.com/

I'm planning to add a feature that enables the users to mark movies and TV shows as favorites and add them to watchlist as a guest (without signing in with TMDb). These data will be saved in the device on a local database. And then later on if the user decides to sign in with a TMDb account, the data in the local database will be added to the TMDb profile.

Is there any (preferably efficient) way to do this other than sending one request per each item..? depending on the number of movies and TV shows in the local database, this could end up being a process that makes a high number of requests.

I'm just trying to review my options. I will be adding the guest profile feature either way. But if there was an easy and efficient way to mark multiple favorites or watchlist items with a single request, I would also be able to add a data synchronizing feature. Thereby bridging the gap between the guest and TMDb user profiles.